Honoo Satake

RESTRUCTURING OF THE BLEOMYCIN METAL CORE. NOVEL OXYGEN-ACTIVATING LIGANDS WITH SYMMETRIZED STRUCTURE

Abstract Novel ligands having symmetrized coordination environment consisting of two histidine units and a pyridine are prepared. Oxygen activating efficiency of the iron complexes of the synthetic ligands increases by introducing electron donating substituent into the pyridine ring.

An artificial CuII complex with intriguing oxygen radical-quenching profile. X-ray structure, cytochrome c assay, and ESR study.

A novel artificial peptide named HPH-Pep, comprising a pyridine and two histidine units, was synthesized. The HPH-Pep-CuII complex had unique pentacoordinated structure as shown by X-ray crystallography and exhibited superoxide-scavenging activity as indicated by ESR spectroscopy. The superoxide-quenching profile of HPH-Pep-CuII was studied in detail by cytochrome c assay and ESR spin trapping and it was found that (1) HPH-Pep-CuII did not scavenge hydrogen peroxide or hydroxyl radical and hence the scavenging activity was specific to superoxide, and (2) HPH-Pep-CuII did not generate hydrogen peroxide upon scavenging superoxide.

Neuropeptides and their receptors of the protochordate, Ciona intestinalis: the evolutionary origin of vertebrate neuropeptides.

Ci-TK and Ci-TK-R are authentic tachykinin (TK) and TK receptor isolated from a protochordate, Ciona intestinalis. In this study, we investigated a novel function of TK as an enhancer of oocyte growth. Ci-TK-R is expressed specifically in the Ciona vitellogenic oocytes. Moreover, administration of Ci-TK to the Ciona ovary resulted in upregulation of gene expression and enzymatic activity of several proteases. Moreover, maturation of the Ciona oocytes from the vitellogenic stage to the post-vitellogenic stage was induced in the presence of Ci-TK, which was completely blocked by addition of protease inhibitors.

Ascidians: New Model Organisms for Reproductive Endocrinology

Ovarian functions, including growth of oocytes and follicles, are believed to involve coordinated and multistep biological events that undergo functional regulation by a wide range of endogenous factors. Mammalian follicles consist of one oocyte surrounded by granulosa cells and theca cells (Orisaka et al., 2009). Mammalian follicular growth is basically classified into two phases: gonadotropin-independent and gonadotropindependent stages. The former includes early follicular growth stages, namely, primordial, primary, secondary, preantral, and antral stages, whereas follicle recruitment, selection, and ovulation occur during the latter. A great variety of intraovarian and extraovarian factors such as a pituitary hormone, gonadotropin, have been well structurally and functionally elucidated. In contrast, no signaling molecules responsible for gonadotropin-independent oocyte growth have ever been identified. ”Neuropeptides” and ”non-sexual peptide hormones” are promising candidates for regulators of early follicle growth, given that many of their receptors were found to be expressed in the ovary. Nevertheless, biological effects of neuropeptides and non-sexual hormones on the ovary still remain controversial or unknown. Such inconclusive data resulted primarily from the difficulty in elucidating in vitro and in vivo physiological functions of neuropeptides or non-sexual hormones in the mammalian ovaries due to heterogeneous quality of oocytes (the very small number of successfully growing oocytes), the low basal levels of receptor expression, and complicated sexual periods (Candenas et al., 2005; Satake & Kawada, 2006a; Debejuk, 2006; Wang & Sun 2007). Furthermore, most receptors of peptide ligands are not ubiquitously, but widely expressed, and thus, neuropeptides and peptide hormones have multiple biological roles, which frequently caused great difficulties in discriminating direct actions on the ovary from indirect actions of a peptide during functional analyses via in vivo administration or using a peptideand/or a receptor-knockout mouse. In such cases, model studies using lower organisms, such as a fruitfly Drosophila melanogaster or a nematode Caenorhabditis elegans, may be useful as the primary step for studies on the biological sciences of mammals. Nevertheless, most invertebrate neuropeptides and hormones possess species-specific primary structures and biological activities. This has hindered comparative analysis and application of traditional invertebrate models to neuroscience and endocrinology research involving neuropeptides and hormones in mammals. These issues suggest a potential

Lignan Biosynthesis for Food Bioengineering

Abstract Functional supplements from dietary or medicinal plant sources are expected to contribute a great deal to extension of health expectancy and improvement of quality of life in the emerging elderly society. Lignans are structurally and functionally diverse phytochemicals and have been widely investigated for the development of healthy diets as well as clinical agents. Recent studies have revealed multiple novel lignan-biosynthetic pathways, the genomes and transcriptomes of lignan-rich plants, and exogenous factors for lignan biosynthesis, which is expected to lead to the efficient, sustainable, and stable production of lignans in plants. This chapter presents the essences of biosynthetic pathways and biological activities of lignans, genomes, and transcriptomes of typical lignan-rich plants, the latest metabolic engineering of lignan biosynthesis, and the perspectives in the metabolic engineering-based production of dietary lignans.